Switch box having plug-in means



Nov. 7, 1933. E. G. K. ANDERSON 1,934,024

swITcH Box HAVING PLUG-'1N MEANS 'Filed May 27, 1932 2 sheets-sheet 1Nov. 7, 1933.

E. G. K. ANDERSON SWITCH BOX HAVING PLUG-IN MEANS Filed May 27, 1952 2sheets-sheet 2 Patented Nov. 7, 1933 FFIC SWITCH Box HAVING PLUG-1NMEANS` Ernst G. K. Anderson, Evanston, Ill., assigner to AppletonElectric' Company, a' corporation of Illinoisl Application May 2v, 1932.serial-No. 613,820

3k Claims.

The object of thepresent invention is to produce a simple and novelswitch box provided withmeans for plugging in-a cable, which will makeit necessary that the switch be open before the plug can be disconnectedafter a coupling has once been made.

A further object of thel present invention is toy provide a plug and acooperatingsocket whose contacts make a sliding engagement with eachother in the direction of the length of the device with means tointerlock the plug and socketv so as to compel them to be rotatedrelatively to each' other afterl the contacts have been separated inorder to disconnect the plug and socket from each other;vtherebyinsuring that arcing at the contacts will have ceased before theoutside atmosphere' can enter.

The' various features of novelty whereby my invention is characterizedwill hereinafter be pointed out with particularity in the claims but,-for a fullY understanding of my invention' and of its objects andadvantages; reference may be had to the' followingv detailed descriptiontaken in connection with the accompanying drawings,- wherein: f-

Figure 1 is a front elevation of a device embodying the presentinvention; Fig.v 2 is aside elevationof the' device, parts being insection; Fig. 3 is? asecti'o'n on line 3- 3v of Fig. 2, on a somewhatlarger-scale than Figs'. 1 and.A 2; Fig. 4 is an end View' of thesocketY member Von the box, on' the same scale as Fig. 3; Fig. 5 is ane'nd View of the' plug member vadapted td be erig'a'gecl with thesocket; Fig. 6 isanelevation of a fragment of a plug member ;J and Fig.'l is a view' showing the opposite end of the socket member from thatwhich appears in Fig. 4.`

Referring to the drawings, 1 represents a switch boxof any usual orsuitable construction; that illustra-ted being one adapted to be securedto a vertical wall# The box may contain aswitchof any usualor suitableconstruction,` the only part of which to which attention need be'called?` beingthe oscillatory handle 2 that projects fromv the' boxproper into a dome-like chamber 3 in the detachable cover 4 of the'box'. The switch is adapted to be operated by a rod or baro slidablymounted in a boss 6 on the cover just below the part 3; `the upper endof the rodi or bar extending into the switch handle chamber and havingthereon a U-'shap'ed por; tion y7 between the arms of which the switch'handle or lever lies.- In other words, asthe actuating' bai' orrodismoved up and' down the switchis4 opened and closed; thev upward move#ment causing the switch to open and the down@ ward movement, of course,`causing the' switch to close.

At the' lower end of the box is a tubular hublike part 8 in which thesocket member of th'e CO, plug and socket connection is iixed. Thissocket member is formed, inv part, of ahollow cylinderor plug 9contracted at its inner or upper end into a neck portion 10'.y The wires11 fromthe switch are led into the member' 9' through thisv 65kv neckportion. Iii the arrangement shown-,there are' three wires. After' thewires have been inserted,- the interior of the neckelement 10 is'filledwith-sealing wax 12L or other suitable corri` position to providea seal. The'interior ofthe' 70 tubular part 8v and the exterior" of themember 9' are machined so as to be a good tand there'- fore, sincev theneckportion 10" is' sealed, there can be no interchange of air or otherga's between the surrounding atmosphere and the .in-Y terior of the boxthrough' the tubular hub on the box. The member" 9 is h'el'd to the bxin any suitable way as, for example",- screws 13 pass'- ing into thesame through the surroundingwallr of the member 9. The outerrt'en'dv 14of the 80 member 9l Ais enlarged somewhat in diameter' to7 produce' aslio'l'ilderv 15 to abut against the lower end of the hub 8' and limitthe distance to whichtheL member 9' can be inserted in' the' hub.

WithinV the member 9z is fixed a body I6A of 85 insulating materialcontaining three tubular conA`- tact pieces 17 extending parallel withthe axisE of said memberi each contact pie'cebeing connected to one ofthe wires 11. In the arrange` ment shown, the member 9j has internalledges 90 or ribs 18 to which the block or body ofinsul'at; ing materialis securedI by' screws" 19. Thel por#` tion of the insulating body `orblock' that lies; outwardly from or below the ledges; 18' is smaller' indiameter than the internal diameter' of the 95 cylindrical part 14.

IIfhe plug element cooperating with th'esocket just described isvcomposed ofa comparatively heavy tubularl part" having in one end a'block or body 21" of insulating material carrying three' 100 projectingpins'2`2'. These pins are' terminals or contact pieces connected' tothewires 23 of a cable 24` that isad'a'pted to 'beel'ectric'ally connecte'dto the switch; A portion of the insulating block 21 lies outwardlybeyo'nd'th'e en'd of 105 the member 20' and fitsV within a cupi-shapedsheet metal shell 24 having in` the bottom a large central openingthrough'which the inher part of the insulating block 2'1 may' pass'.screws 25, extending down through the insuia't- 110 boss.

ing block 21, the remaining portion of the bottom wall of the cup-shapedshell and into bosses 26 within the member 2Q, serve to secure themembers 24, 21 and 20 together. parte are so proportioned that, when theplug and the socket members are brought together, the cylindrical wallof the member 24 fits nicely within the enlarged part 14 oi' the socketmember; the forward end of this cylindrical shell or wall lying betweenthe outer pa t or the block 15 and the surrounding cylindrical part 14.The lower end of the member 14 may externally screw-threaded, asindicated at 27, to be engaged by a cup-shaped nut 2? rotatable on themember 20, and in'terlocked ther i by having an annular in-turned lipengaged under an annular enlargement or collar Si) around the upper endof the member 20. After the plug has been inserted in the socket the nutmay `be screwed up on the part 14 so that a pull on the cable will notcause the plug to become separated from the socket.

When the plug and the socket have been assembled, as shown, arcing atthe switch in opening the same to break the circuit cannot ignitecombustible gases in the surrounding atmosphere because the passagesvtlnough which the conductors of the cable are c iected to the switchare effectively sealed. However, if the circuit is broken by the act ofpulling out the plug, the arcs that may be formed between the Contactpieces 17 and 22 could act directly upon combustible `gases in thevicinity of the device and cause an explosion. I have therefore providedmeans to prevent the separation oi the plug from the socket until theswitch has been opened, so that there is no current flowing when theplug is withdrawn. In the arrangement shown, the part 14 has on thefront side, directly behind the path of movement ci the switch actuator5, a boss 32 provided with a central bore 33 that extends entirelythrough the underlying wall of the part i4. In this bore is located apin 34 having at the outer end a head 35. That part of the bore 33 that,extends through the wall of the part 14 at the inner end of the boss isonly as large in diameter as the pin, whereas the remainder of the bereis of the same diameter as the head oi the pin. Consequently, there isat the inner end of the large portion of the bore a shoulder on whichmay rest a compression spring 36 that surrounds the pin and engages itat its outer end with the under side of the head on the pin. The springis put in under an initial compression so that, when free to do so, itwill push the pin out clearfof the bore at the part 14. The outer end ofthe boss is slotted, as indicated at 37, in the plane of the actuator 5and, in the slot l in the boss, is arranged a lever 33 pivoted at itslower end, as indicated at 39. The upper end of the lever liesunderneath and overlaps the lower end of the switch actuator 5 when theactuator is in its switch-closing position. The extreme lower end ofther switch actuator is Wedge-shaped so as to provide an inclined i'ace40. When the switch actuator is up, in the switch-open position, thelower end thereof is clear of the lever 38 and therefore the springunder the head of the pin 34 iorces the pin outwardly and swings thefree end oi the lever outwardly. The outward movement 'of the lever islimited by a finger 41 on the lower end of theV lever which engages withthe under side 'oi the Then. when the switch actuator is moved down soas to close the switch, the inclined face 40 engages with the upper freeend of the lever and gradually swings the lever in the clockwisedirection, as viewed in Fig. 2; thereby causing the lever to push thepin inwardly, as shown in Fig. 2.

The cylindrical part of the metal shell 24 on the plug member hastherein a hole 42 in position to register with the pin 34 and receivethe inner end oi the pin when the pin is pushed in upon the closing ofthe switch. Therefore, aiter the parts have been assembled, the plugcannot be withdrawn until the switch is opened and the locking pinretracted. Furthermore, if the switch should be closed while the plug isdisccn nected, the coupling cannot be completed until the switch isagain opened, because the pin 34 will act as a stop to engage with theupper end of the member 24 and prevent this member from entering fullyinto the socket. I have also illustrated means to prevent arcing betweenthe contacts in the plug and the socket in the event that the interlockwith the switch is not being used or is not in condition for use. Tothis end, as best shown in Figs. 2, 5 and 6, I have deformed thecylindrical portion of the shell 24 to produce therein a trough-likerecess 43 consisting oi a short outer arm and a long inner armparalleling the axis of the plug and separated frcm each othercircumferentially oi the latter; these two arms being connected by across arm extending circumferentially. Within the part 14 of the socketis a pin 44 in position to cooperate with the bayonet slot or groove. Itwill be seen that, when the plug is inserted in the socket, it can movein a short distance and must then be turned before it is pushed in therest of the way. Similarly, upon withdrawing the plug, it can be pulledout for a distance equal to the length of the long arm or leg of theslot, which is suicient to open the circuit at the contacts in theconnector, and must then be turned before it can be completelywithdrawn. In other words, the circuit is broken and the arcs areextinguished before the space around the contacts in the connector isopened to atmosphere. This interlock, consisting of the pin and thebayonet slot or groove, of course serves the further purpose ofaccurately positioning the plug angularly of its axis to bring the hole42 directly opposite the locking pin or ledge 34.

It should be noted that, if the cover for the switch box were reversed,end for end, the switch could be opened and closed without causing theplug to be locked in the socket while the switch is closed. This may beprevented by so constructing the parts that the cover can be set on thebox in only one way, namely, that which will enable the switch actuatorto control the lock or catch for the connector. This can be accomplishedby such a spacing of the holes for the screws that the screw holes inthe box will not register with those in the cover except in one positionof the cover and by an interlock between the cover and the switch. Inthe arrangement shown, the holes in the cover for the screws 45 arefarther apart at one end of the cover than the other. Also, the switchis provided with a boss or lug 46 that will enter a recess 47 in theinner side of the cover when the cover is properly applied, and notinterfere with the securing of the cover; but which will engage with theinner face of the cover if the latter be turned end for end, and holdthe cover away from the box. Therefore, the switch must T be properlypositioned in the box and the cover must be properly positioned withrespect to the switch in making the assembly.

While I have illustrated and described with particularity only a singlepreferred form of my invention, I do not desire to be limited to theexact structural details thus illustrated and described; but intend tocover all forms and arrangements whch come within the denitions of myinvention constituting the appended claims.

I claim:

l. In combination, a box containing a, switch and having at one side anexternal socket to receive a plug on a cable to be connected to theswitch, a locking device on the socket adapted to engage with a plug inthe socket to lock it against removal, a detachable cover for the box,and a switch actuator slidably mounted in the cover and having a partadapted to engage with the switch when the cover is applied to the boxand having a second part lying outside of the box and adapted to movefrom a position overlying said locking device when the switch is closedto a position clear of the locking device when the switch is open.

2. In combination, a box containing a switch and having at one side asocket to receive a plug on a cable to be connected to the switch, alocking device on the socket adapted to engage with a plug in the socketto lock it against removal, a detachable cover for the box, a switchactuator slidably mounted in the cover to move from a position overlyingsaid locking device when the switch is closed to a position clear of thelocking device when the switch is open, and cooperating means on the boxand the cover to prevent the cover from being applied in any positionexcept that which brings the switch actuator in proper relation to thelocking device.

3. In combination, a switch box having a socket to receive a plug on acable to be connected to the switch in the box, a movable radial pin onthe socket, a spring tending constantly to hold the pin with its innerend clear of the bore in the socket while permitting the pin to bepushed into said bore against the resistance of the spring, a levermounted on the socket and overlying the pin and adapted to force the pininwardly when pressure is applied to the lever, and a switch actuatorslidably mounted on the box in such a position that it moves across thetop of the lever in the direction of the length of the latter during itsswitch-actuating movements, said actuator having a part adapted toengage the lever and press it down when the actuator is moved in thedirection to close the switch. y

ERNST G. K. ANDERSON.

